Design process of green laser diode (LD) end-pumped solid-state laser, finite element method (FEM) is applied for the optimization of temperature controlling performance. Using ANSYS, a finite element analysis software, we do thermal analysis of the temperature controlling structure by steady-state thermal simulation and transient thermal simulation and optimize the structure on the basis of analytic result. The results show that with the cooling capacity in the same input, the temperature controlling capacity of the optimized temperature controlling structure arises approximately 10%, showing a significant improvement over the initial structure. An experimental setup on the basis of optimized structure is made and its temperature controlling capacity is tested. The error between the experimental data and ANSYS thermal simulation data is less than 5%. The results show that finite element analysis has a significant effect on improving the temperature controlling performance of green laser diode end-pumped solid state laser.